The present invention relates to a system for detecting and recording voltages or voltage pulses of predetermined amplitude and/or time duration, and to the use of such system for monitoring the environmental "G" forces experienced by a given munition or other device during a given time.
One of the major problems in the development of munitions has been the inability to obtain satisfactory data on the actual field transportation environment the item experiences from point of origin to point of end use. Without this data it is very difficult to specify with any confidence the ideal design and performance specifications. As a result, most munitions are over-designed and often unnecessarily rejected during production tests. This has reduced the overall cost effectiveness of munition programs. In the past, the only way to estimate the field environment was to perform an extensive and costly series of worst case laboratory tests.
In accordance with the invention, a small self-contained package, containing a piezoelectric transducer, a detection and recording circuit and battery, is designed to be implaced within an explosive shell, for example, to monitor and record all environmental G forces of given amplitude and/or time duration that the shell is subjected to during a given time. Any conventional small piezoelectric transducer may be used. The detection and recording circuit comprises a novel circuit for detecting each voltage pulse from the piezoelectric transducer that is at least equal to a predetermined amplitude, and/or a novel circuit for detecting each voltage pulse that has a time width at least equal to a predetermined width, and means for recording the detected pulses. The amplitude detection means comprises a pair of input terminals, two resistors, a voltage comparator, and means connecting the two resistors in series and parallel with the input terminals and comparator. The pulse width detection circuit comprises a pair of input terminals, a positively-triggered monostable, a positive-triggered clock flip-flop, and suitable connecting means. Preferably, the flip-flop is provided with an RC means for automatically terminating the output pulse after a predetermined delay. The detected pulses are recorded by a digital counter .